(A) Field of the Invention
The present invention relates to an optoelectronic system for sensing an electric field signal, and more particularly, to an optoelectronic system for sensing an electric field signal that can avoid interference on sensing the spatial distribution of the electric field.
(B) Description of the Related Art
Technologies such as wireless communication and radio-frequency identification (RFID) must use antennae to emit electric field signals, and methods of meeting antenna emission field pattern requirements becomes an important topic on improving the product quality. An electric field signal can be sensed in many ways, including modulated scatterer technology for sensing the distribution of an electric field. Related arts have been published for decades, from the document “A modulated scatterer technique . . . -1955, IRE Trans. on microwave distribution” written by Richmond, J. H. to current updates such as U.S. Pat. No. 4,552,151 and U.S. Pat. No. 5,430,369.
The technologies described in the above documents all employ conductive wires to modulate and bias diodes inside a scatterer and also utilize a fast scan scheme so as to sense an electric field. As the wires for transmitting control signals may generate some electric field, the biasing operation of the diodes inside the scatterer through wires may interfere with the electric field signal to be sensed. This problem is particularly important for the accuracy of electric wave sensing (especially for micro antennae).
Furthermore, the technologies disclosed in U.S. Pat. No. 4,552,151 and U.S. Pat. No. 5,430,369 generally use a conventional antenna to receive a scattering signal and then transmit the signal to a signal processing circuit through a cable. The cable contains metal, which may affect the received scattering signal, thus causing a distortion of scattering signal. Therefore, the conventional receiving antenna cannot be placed closely to the scatterer configured to generate the scattering signal so as to avoid signal coupling.